/*
 * Copyright (C) 2016 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.graph;

import static com.google.common.graph.GraphConstants.GRAPH_STRING_FORMAT;

import com.google.common.annotations.Beta;
import javax.annotation.Nullable;

/**
 * This class provides a skeletal implementation of {@link Graph}. It is recommended to extend this
 * class rather than implement {@link Graph} directly.
 *
 * @author James Sexton
 * @param <N> Node parameter type
 * @since 20.0
 */
@Beta
public abstract class AbstractGraph<N> extends AbstractBaseGraph<N> implements Graph<N> {

    @Override
    public final boolean equals(@Nullable Object obj) {
        if (obj == this) {
            return true;
        }
        if (!(obj instanceof Graph)) {
            return false;
        }
        Graph<?> other = (Graph<?>) obj;

        return isDirected() == other.isDirected() && nodes().equals(other.nodes()) && edges().equals(other.edges());
    }

    @Override
    public final int hashCode() {
        return edges().hashCode();
    }

    /** Returns a string representation of this graph. */
    @Override
    public String toString() {
        String propertiesString = String.format("isDirected: %s, allowsSelfLoops: %s", isDirected(), allowsSelfLoops());
        return String.format(GRAPH_STRING_FORMAT, propertiesString, nodes(), edges());
    }
}
